Liquid desiccant air conditioning systems and methods

Abstract

Methods and systems are provided for air conditioning, capturing combustion contaminants, desalination, and other processes using liquid desiccants.

The invention claimed is: 
     
       1. A liquid desiccant air conditioning system operable in a warm weather operation mode and/or a cold weather operation mode for treating an air stream entering a building space, comprising: a conditioner including a plurality of structures arranged in a substantially parallel orientation, said plurality of structures being spaced apart from each other with an air stream gap between each pair of adjacent structures, each of the plurality of structures having at least one outer surface facing an air stream gap across which a liquid desiccant flows, wherein the air stream flows through the air stream gaps between the plurality of structures such that the liquid desiccant dehumidifies the air stream in the warm weather operation mode and humidifies the air stream in the cold weather operation mode, wherein each of the plurality of structures includes a passage therein through which a conditioner heat transfer fluid flows, the conditioner heat transfer fluid for cooling the liquid desiccant used in the conditioner in the warm weather operation mode and heating the liquid desiccant used in the conditioner in the cold weather operation mode, the conditioner further comprising one or more liquid desiccant collectors for collecting the liquid desiccant that has flowed across the at least one outer surface of each of the plurality of structures; a regenerator connected to the conditioner for receiving the liquid desiccant used in the conditioner, treating the liquid desiccant, and returning the liquid desiccant to the conditioner, wherein the regenerator treats the liquid desiccant by causing the liquid desiccant to desorb water in the warm weather operation mode and to absorb water in the cold weather operation mode; a liquid desiccant heat exchanger connected between the conditioner and the regenerator for transferring heat from the liquid desiccant flowing from the regenerator to the conditioner to the liquid desiccant flowing from the conditioner to the regenerator in the warm weather operation mode, and for transferring heat from the liquid desiccant flowing from the conditioner to the regenerator to the liquid desiccant flowing from the regenerator to the conditioner in the cold weather operation mode; a heat pump for heating the liquid desiccant flowing from the conditioner to the regenerator and cooling the liquid desiccant flowing from the regenerator to the conditioner in the warm weather operation mode, and for cooling the liquid desiccant flowing from the conditioner to the regenerator and heating the liquid desiccant flowing from the regenerator to the conditioner in the cold weather operation mode; an apparatus for moving the air stream through the conditioner; and an apparatus for circulating the liquid desiccant between the conditioner and the regenerator. 
     
     
       2. The liquid desiccant air conditioning system of  claim 1 , wherein each of the plurality of structures includes a sheet of material positioned proximate to the at least one outer surface of each of the plurality of structures between the liquid desiccant and the air stream, each sheet of material permitting transfer of water vapor between the liquid desiccant and the air stream. 
     
     
       3. The liquid desiccant air conditioning system of  claim 1 , further comprising a cold source for cooling the conditioner heat transfer fluid in the warm weather operation mode, and a heat source for heating the conditioner heat transfer fluid in the cold weather operation mode. 
     
     
       4. The liquid desiccant air conditioning system of  claim 1 , wherein the heat pump includes heat exchanger coils for directly heating the liquid desiccant in the cold weather operation mode and directly cooling the liquid desiccant in the warm weather operation mode. 
     
     
       5. The liquid desiccant air conditioning system of  claim 1 , further comprising an evaporative chiller connected to the conditioner for receiving at least a portion of the dehumidified air stream exiting the conditioner in the warm weather operation mode, and wherein the evaporative chiller is configured to cause the portion of the dehumidified air stream to absorb water from a water source and thereby cool the conditioner heat transfer fluid cool the air stream in the conditioner. 
     
     
       6. The liquid desiccant air conditioning system of  claim 1 , wherein the plurality of structures in the conditioner have a substantially vertical orientation. 
     
     
       7. The liquid desiccant air conditioning system of  claim 1 , wherein the regenerator includes a plurality of regenerator structures arranged in a substantially parallel orientation, said plurality of regenerator structures being spaced apart from each other with an air stream gap between each pair of adjacent regenerator structures, each of the plurality of regenerator structures having at least one outer surface facing an air stream gap across which the liquid desiccant flows, wherein the air stream flows through the air stream gaps between the plurality of regenerator structures such that the liquid desiccant humidifies the air stream in the warm weather operation mode and dehumidifies the air stream in the cold weather operation mode. 
     
     
       8. The liquid desiccant air conditioning system of  claim 7 , wherein each of the plurality of regenerator structures includes a sheet of material positioned proximate to the at least one outer surface of each of the plurality of regenerator structures between the liquid desiccant and the air stream, each sheet of material permitting transfer of water vapor between the liquid desiccant and the air stream, wherein each of the plurality of regenerator structures includes a passage therein through which a regenerator heat transfer fluid flows, the regenerator heat transfer fluid for heating the liquid desiccant used in the regenerator in the warm weather operation mode and cooling the liquid desiccant used in the regenerator in the cold weather operation mode, the regenerator further comprising one or more liquid desiccant collectors for collecting liquid desiccant that has flowed across the at least one outer surface of each of the plurality of regenerator structures. 
     
     
       9. The liquid desiccant air conditioning system of  claim 8 , wherein the heat pump heats the conditioner heat transfer fluid and cools the regenerator heat transfer fluid in the cold weather operation mode, and wherein the heat pump heats the regenerator heat transfer fluid and cools the conditioner heat transfer fluid in the warm weather operation mode. 
     
     
       10. The liquid desiccant air conditioning system of  claim 1 , further comprising a tank for storing the liquid desiccant, wherein the liquid desiccant varies in concentration along the height of the tank, and a drain for drawing the liquid desiccant from the tank at different selected heights of the tank in order to obtain liquid desiccant having a desired concentration for use in the conditioner. 
     
     
       11. A method of using a liquid desiccant air conditioning system for treating an air stream entering a building space, the liquid desiccant air conditioning system including a conditioner, a regenerator, and a heat pump, wherein the conditioner includes a plurality of structures arranged in a substantially parallel orientation, said plurality of structures being spaced apart from each other with an air stream gap between each pair of adjacent structures, each of the plurality of structures having at least one outer surface facing an air stream gap, each of the plurality of structures including a passage therein, the method comprising: (a) flowing a liquid desiccant across the at least one outer surface of each of the plurality of structures and flowing a conditioner heat transfer fluid through the passage of each of the plurality of structures to cool the liquid desiccant flowing across the at least one outer surface in a warm weather operation mode and to heat the liquid desiccant flowing across the at least one outer surface in a cold weather operation mode; (b) flowing the air stream to be provided to the building space through the air stream gaps between the plurality of structures such that the liquid desiccant dehumidifies the air stream in the warm weather operation mode and humidifies the air stream in the cold weather operation mode; (c) collecting the liquid desiccant that has flowed across the at least one outer surface of each of the plurality of structures and transferring the liquid desiccant to a regenerator; (d) causing the liquid desiccant to desorb water in the warm weather operation mode and to absorb water in the cold weather operation mode in the regenerator; (e) heating the liquid desiccant flowing from the conditioner to the regenerator and cooling the liquid desiccant flowing from the regenerator to the conditioner in the warm weather operation mode using the heat pump; and cooling the liquid desiccant flowing from the conditioner to the regenerator and heating the liquid desiccant flowing from the regenerator to the conditioner in the cold weather operation mode using the heat pump; and (f) transferring heat from the liquid desiccant flowing from the regenerator to the conditioner to the liquid desiccant flowing from the conditioner to the regenerator in the warm weather operation mode, and transferring heat from the liquid desiccant flowing from the conditioner to the regenerator to the liquid desiccant flowing from the regenerator to the conditioner in the cold weather operation mode using a liquid desiccant heat exchanger. 
     
     
       12. The method of  claim 11 , wherein each of the plurality of structures includes a sheet of material positioned proximate to the at least one outer surface of each of the plurality of structures, each sheet of material permitting transfer of water vapor between the liquid desiccant and the air stream, and wherein step (b) comprises flowing the liquid desiccant between the sheet of material and the at least one outer surface of each of the plurality of structures. 
     
     
       13. The method of  claim 11 , further comprising cooling the conditioner heat transfer fluid in the warm weather operation mode, and heating the conditioner heat transfer fluid in the cold weather operation mode. 
     
     
       14. The method of  claim 11 , wherein step (e) comprises directly heating the liquid desiccant and directly cooling the liquid desiccant using heat exchanger coils in the heat pump. 
     
     
       15. The method of  claim 11 , further comprising diverting at least a portion of the dehumidified air stream exiting the conditioner in the warm weather operation mode and causing the portion of the dehumidified air stream to absorb water from a water source and thereby cool the conditioner heat transfer fluid to cool the air stream in the conditioner. 
     
     
       16. The method of  claim 11 , wherein the regenerator includes a plurality of regenerator structures arranged in a substantially parallel orientation, said plurality of regenerator structures being spaced apart from each other with an air stream gap between each pair of adjacent regenerator structures, each of the plurality of regenerator structures having at least one outer surface facing an air stream gap across which the liquid desiccant flows, wherein step (d) comprises flowing the air stream through the air stream gaps between the plurality of regenerator structures such that the liquid desiccant humidifies the air stream in the warm weather operation mode and dehumidifies the air stream in the cold weather operation mode. 
     
     
       17. The method of  claim 16 , wherein each of the plurality of regenerator structures includes a sheet of material positioned proximate to the at least one outer surface of each of the plurality of regenerator structures, each sheet of material permitting transfer of water vapor between the liquid desiccant and the air stream, and wherein step (d) comprises flowing the liquid desiccant between the sheet of material and the at least one outer surface of each of the plurality of regenerator structures. 
     
     
       18. The method of  claim 11 , further comprising storing the liquid desiccant in a tank, wherein the liquid desiccant varies in concentration along the height of the tank, and drawing the liquid desiccant from the tank at a given selected height of the tank in order to obtain liquid desiccant having a desired concentration for use in the conditioner. 
     
     
       19. The method of  claim 16 , wherein each of the plurality of regenerator structures includes a passage therein, and wherein step (d) further comprises flowing a regenerator heat transfer fluid through the passage of each of the plurality of regenerator structures to heat the liquid desiccant flowing across the at least one outer surface in the warm weather operation mode and to cool the liquid desiccant flowing across the at least one outer surface in the cold weather operation mode. 
     
     
       20. The method of  claim 19 , wherein step (e) comprises heating the conditioner heat transfer fluid and cooling the regenerator heat transfer fluid in the cold weather operation mode using the heat pump, and heating the regenerator heat transfer fluid and cooling the conditioner heat transfer fluid in the warm weather operation mode using the heat pump.